MICROANATOMY

Detailed explanation-1: -Fibrin forms long strands of tough insoluble protein that are bound to the platelets. Factor XIII completes the cross-linking of fibrin so that it hardens and contracts. The cross-linked fibrin forms a mesh atop the platelet plug that completes the clot.

Detailed explanation-2: -The fibrin network is the main structural component of the blood clot and stabilizes the platelet plug that forms upon a vascular injury (3, 7–10). The formation of the network occurs in a sequence of steps, starting with the conversion of fibrinogen to fibrin, enzymatically catalyzed by thrombin (11, 12).

Detailed explanation-3: -The proteins collagen and thrombin act at the site of the injury to induce platelets to stick together. As platelets accumulate at the site, they form a mesh that plugs the injury.

Detailed explanation-4: -Factor IIa (thrombin) goes on to activate fibrinogen into fibrin. Thrombin also goes on to activate other factors in the intrinsic pathway (factor XI) as well as cofactors V and VIII and factor XIII. Fibrin subunits come together to form fibrin strands, and factor XIII acts on fibrin strands to form a fibrin mesh.